Collars, nuts, or other locking mechanisms are used to secure one object to another. In the oil and gas industry, for example, a stuffing box is threaded into a flange of a well head and is secured to the well head with a threaded locking collar. With time, exposure, and wear, the locking collar degrades and becomes permanently attached to the flange of the well head and the stuffing box such that the locking collar cannot be easily removed. It then becomes very difficult to remove the stuffing box from the well head.
One technique for removing the locking collar involves using a sufficiently long pipe wrench and manually applying torque to the locking collar. It is very difficult, if not impossible, for one or more individuals to generate sufficient torque to loosen the locking collar. Using such a pipe wrench also poses safety issues. Furthermore, the space around many well heads is insufficient to use a sufficiently long pipe wrench.
Another technique for removing the locking collar calls for the assistance of a separate bolting crew, which will come and remove the well head itself, or some part thereof. The bolting crew will then take the well head offsite where it can employ specialised tools to attempt to unlock the locking collar so as to remove the stuffing box. Such a technique necessarily involves significant down time during which the well head is not productive, which represents an important additional expense.